Air Conditioner & Microwave

I have read so much about 30 amp basically not being able to run both a/c & other high draw items at the same time.  I understand that shutting stuff off does work, but when it is 90+ and we shut the a/c off to use micro for any length of time, it gets hot fast.  Anyone install an easy start on the a/c?

Thanks, Bob

 Mrs V uses the microwave with the AC on in our 2350.  30A service.  What breaker is tripping when you do so?


 Make sure the Water heater is on GAS or turned off if you are trying to use the micro and AC together. That was an issue a few times we kept on popping the pole. 

But BEFORE we figured out the water heater was our nemesis, I researched soft starts/easy starts, I was intrigued by this product -

https://www.microair.net/products/easystart-364-3-ton-single-phase-soft-starter-for-air-conditioners?variant=30176048267

Costs a LOT more than the 'large capacitor' soft starts ($300 vs $20!)   but appeared to be a well engineered solution.   

Dometic 13500  Penguin uses 1731 W
Sharp R820 microwave  uses 1550 W

total load @ 120v = 27.3 A
total load @ 110v = 29.8 A

We run both with no problem, shore power or generator.

A 30 amp Hughes Autoformer will boost the shore power pole voltage and supply 3600 watts, plus provide surge protection for around $450.  But if your generator output voltage is low check the generator rpm and/or voltage regulator.

Agree with others, generator or shore power "should" be OK.  We use a 'Good Governor' voltage and frequency meter.  It plugs into a standard 120v outlet.  We use the one below the generator controls behind the driver area.  You don't want voltage to drop below 105.   Some campground pedestals start out at just 110v.  If you get one like that, you won't be able to run both.   On your generator, watch the frequency, you don't want it below 58 cycles per second.   If running both a/c and microwave slows your generator to 57 or lower, take your RV to an Onan (Cummings) dealer and have them give it a tune up and adjust the controls.

And do not use your hot water heater via electricity heating... Use propane only.

Don

Don, does this apply to the new Truma unit they installed in the 2351D's?

Thanks for all the tips.  Should I also run the frig on propane only and well as the hot wtr htr?  I will have to check the breaker it is tripping.  I know it's a 20 amp.  Have to get on my knees with a flash light.  Aging ain't fun.

Finally got around to eye balling the exact breaker.  It is the 20 amp air conditioning breaker that keeps poping.  I am hooked to house electricity (50 amp) with reducer to 30.  I will run a couple different scenarios and see what happens.

Don, does this apply to the new Truma unit they installed in the 2351D's?

I don't know but if the Truma uses electricity to heat the water, I would definitely say yes.. Do not have microwave, A/C and Truma all on at once.

If the Truma heats with propane, I would be comfortable using all 3 at once.

Bangorbob.. The refrigerator 120v heater is probably OK.   I have never had an issue with either shore power or generator power and running all 3..refrigerator on 120v, a/c and microwave at once.  But then I never use the microwave for more than 5 minutes, never use as a convection oven and it's certainly possible the refrigerator never came on while using the other 2.   I can tell you for sure that just a/c and refrigerator is fine.  When going to an automobile race track... I often have to run generator 8 to 12 hrs a day with a/c on and never had an issue.

Don

Our rig is 30 amp. Our fridge is always on auto which sets to electric when we are plugged in so it's always on. We've had AC plus microwave (either as convection oven or microwave) going at the same time numerous times, sometimes for long periods. We make sure the water heater is off but often have little things drawing electric at the same time: device chargers, battery chargers, etc. I don't add the instant pot to the mix. No problem with tripping breakers.

We rarely have 30amp service in the places we stay at, so 110V in our PC is most often in the morning running our generator for house battery recharging.  During that time, we have the coffee maker brewing, charging cell phones and other batteries, and our Black & Decker battery charger is hooked up to the house batteries.  I use the B&D charger because I can reduce generator time compared to the on board Tripp-Lite converter/inverter.  It also has a nice charging amperage display to tell me how close to "fully charged" I am when shutting down the generator.

When Irene wants to microwave something during that time, we turn off the coffee maker.  Otherwise it is a hit or miss if the over-load protection switch on the generator will "trip".  Then I have to remove the generator cover and flip it back.

I hope everyone here knows about that Onan overload protection switch on the generator.  It is located on the side of the area where the start switch is.  You'll miss it if not looking hard for it.

Same here.  I've also got an '08 2350 and we've never seen a tripped breaker.  I'm a former electrician, so I've actually wondered why not at times.  We always stay in RV parks, so we're always A/C on everything -- hot water tank,A/C, fridge, microwave (not mention hair dryer and Kuerig).   We did trip the 20a breaker on the recep in my carport one time in our driveway, while unloading.  I'd forgotten to turn off the hot water tank.

If your A/C is tripping the 20a breaker in the motorhome, I'd say there is a problem with the A/C, not the 30a service.  If you're drawing more than 30, it will trip the breaker on the power pole.

Same here.  I've also got an '08 2350 and we've never seen a tripped breaker.  I'm a former electrician, so I've actually wondered why not at times.  We always stay in RV parks, so we're always A/C on everything -- hot water tank,A/C, fridge, microwave (not mention hair dryer and Kuerig).   We did trip the 20a breaker on the recep in my carport one time in our driveway, while unloading.  I'd forgotten to turn off the hot water tank.

If your A/C is tripping the 20a breaker in the motorhome, I'd say there is a problem with the A/C, not the 30a service.  If you're drawing more than 30, it will trip the breaker on the power pole.

Although I am not or never was an electrician I grew up with one.  My Dad.  He did teach some things-some the hard way.   Anyway, that's why my original post ask about the easy start product. 
r/Bob

Dometic 13500  Penguin uses 1731 W
Sharp R820 microwave  uses 1550 W

total load @ 120v = 27.3 A
total load @ 110v = 29.8 A

We run both with no problem, shore power or generator.

A 30 amp Hughes Autoformer will boost the shore power pole voltage and supply 3600 watts, plus provide surge protection for around $450.  But if your generator output voltage is low check the generator rpm and/or voltage regulator.

I am certainly not an electrical engineer or electrician (my father was an electrical engineer) the wattage (actual power) is the result of multiplying Volts times Amps.   To get the same power (as your posting shows) if you lower the voltage, you must raise the amperage.

An auto transformer "fixes" the power TO an electrical device by raising or lowering its output voltage to an appropriate value (say 120v) and maintains that output voltage for fairly wide swings in its input voltage.  That prevents electrical "wear and tear" on devices connected to the auto transformer.  That's nice.

The problem is #1 The Auto Transformer (like all things) isn't 100% efficient.. It draws a little more input power than it outputs.  Thus.. #2 The Auto Transformer must draw more power from your generator or shore power source than you are using so it is quite possible to overload the input to the Auto Transformer and cause the pedestal breaker or your generator breaker to trip even though your a/c and microwave see "ideal" voltage and amperage.    Obviously low pedestal voltage or generator voltage is worse than high voltage (to a limit).

Which is why I act as my own auto transformer and monitor input voltage and frequency whether from the generator or the pedestal.  Below 105v I watch constantly while the microwave is running, below 102v...I shut the microwave (or a/c) down.  I use a surgeguard on pedestal power which will shut off at over 130v or under 100v.

An Auto Transformer will "watch" the line and adjust, as needed, constantly.   That's a very good thing.   But it won't stop you from causing a circuit breaker to open at your generator or pedestal.

Just be aware of the limitations.

Don

Quote from: BlueBlaze on August 29, 2020, 03:14:47 pm

Same here.  I've also got an '08 2350 and we've never seen a tripped breaker.  I'm a former electrician, so I've actually wondered why not at times.  We always stay in RV parks, so we're always A/C on everything -- hot water tank,A/C, fridge, microwave (not mention hair dryer and Kuerig).   We did trip the 20a breaker on the recep in my carport one time in our driveway, while unloading.  I'd forgotten to turn off the hot water tank.

If your A/C is tripping the 20a breaker in the motorhome, I'd say there is a problem with the A/C, not the 30a service.  If you're drawing more than 30, it will trip the breaker on the power pole.

Although I am not or never was an electrician I grew up with one.  My Dad.  He did teach some things-some the hard way.   Anyway, that's why my original post ask about the easy start product. 
r/Bob

An Easy Start would probably solve the problem short term, but I think if the A/C is drawing a startup surge large enough to kick the breaker, it's a symptom of something going wrong.